Process for drying or cooling granular materials.



E. BORNMANN.

PROCESS FOR DRYING 0B. COOLING GRANULAR MATERIALS. APPLIOATION I'ILBD OUT. 29, 1913.

1,102,714. Patented July 7, 1914.

W7 wl a6 3 UNITED snares PATENT- O ar.

nmrsrr nonmanujor, must, cannery, AssIeNon 'ro rim F RM-or J. A, Torr-a summit, or Enrnnr, GERMANY. I rnoons's ronrnnne-on COOLING GEANULAB MATERIALS;

To all when? cdncem: Be it known that I, ERNST BOHNMANN,

engineer, a subject of the German Emperor,

residing at Erfurt, Empire of Germany,

5 have invented certain new and useful Improvements in Processes for Drying or CoolingGranular Materials,'of whlch the followmg is a specification.

The present lnvention'relates to a process ,for drying or cooling granular material of tower apparatus the-drying medium passes through the material. in the opposite direction to that of themovement of the material itself but it has also been proposed, in addltion, to subject the portion of the material which has already been treated in this way,

to the effect of a current of drying medmm passing through it in the direction in which it periodically moves itself.

According to the invention, the materlal is treated in this kind ofapparatus as an inclosed mass of uniform epth over the Whole cross-section of the apparatus and it I is caused to pass entirely through the apparatus in the same direction as the drying medium, as has been proposed in that type of apparatus in which the material is treated in thin layers upon sloping surfaces.

In this way the heat, which is imparted to the layers of the material .to be dried, upon which the drying medium first impinges, is

given up in the course of the drying process to the drying medium which becomes cooled owing to its increasing saturation. This efi'ect takes place because the drying air in 40 the shaft-like apparatus is forced to. pass completely and uniformly through all layers of the material which-is fed in at the top and continues to trickle down' uniformly. By this process, there is a considerably higher drying effect with a decreased ;A.:-* honsl1mption of-heat. The material. to be dried may be steadily maintained in a column the dtepth of which is adjustable b the use of ba es in conjunction with an a justable feeding device, and at thesame time the degree of saturation of the drying air may be adjusted. The baflies may be conical plates sloping toward the center or toward the circumference as has been employed in drying kilns in which hot air suppliedfrom Specification of Letters, IPatent. Application filed October 2 9, 1918, smia No, 798,033, 1

' Patented July 7, 1914.

above passes radially. outward through a thin annular vertical column of the material trickling down under treatment. The baflles also serve to keep the depth of the thickness of the columrrof material trickling down the same as above mentioned over the whole ofthe breadth of the apparatus so that a uniform current of air is present.

The drawing shows diagrammaticallya section through an apparatus for carrying out the process according to the invention.

The material to be dried is placed in a shaft-shaped. container a of any desired form of cross-section through any desired removable feed device I) which is formed in the example illustrated as a removable supply tube provided with a funnel top.

The discharge of the material takes place through the outlet pipe 0 at d. The crosssection of the outlet at d can be Varied through any deslred means and thereby the speed of the passing out of the material and the passing in (through pipe b and there,

by, too, according to the period of time dur ing which the material remains in the apparatus, the drying is controlle A sloping afile e, permeable to air, in the example illustrated as conical, promotes a symmetrical flowing movement as wellas the mixing ofthe material to be dried. The gradient of the conical bafiie e is made in accordance with the angle of repose of the material to be dried in order to insure that the height of the layer of the material is uniform over the. whole cross-section of the apparatus so that a current of air takes place uniformly over the whole cross-section of the apparatus. In order to maintain this operation and -to' supply the drying air, a second conical permeable baffle 7, arranged below the firstnamed, serves. By means of the baflies e, f,

which may be fixed or movable, in conjunction with the adjustable feeding device Z), the material to be dried is maintained as an inclosed mass continually uniformly tricklink down, the thickness being adjustable.

, By adjustment of the thickness of the layer the saturatlon of the drying air is correspondingly adjusted. The lower part of the container a bounded by the baflie f isp'laced in connection with a suction air pump it. The drying medium (air or gas) is warmed in a heater 9 of any desired construction connected in desired manner to the drying apparatus and is drawn through the air pump h in a constant stream in the same direction with the material.

The point at which the drying air passes into the container is so arranged that the air steadily acts upon the material -to be dried from above, and acts particularly to constantly warm the top-most layers of the same. In these layers the drying air beromes comparatively little saturated. Its temperature and therefore also that of the material to be dried remains greater'here than in the lower layers. When the mate rial to be dried sinks downthen these warmer layers re-act upon the drying air which has become cooler owing to the increasing saturation, consequently it raises its temperature and thereby it renders it capable of taking up more moisture.

In order not to interfere with the dis charge of the materialto be dried. fat the outlet d owing to the back pressure prevailing in the lower part of the a paratus a; suitable adjustable and closableau; inlet de vice i is arranged at; a suitable point above, the outlet, for example on'the *outletpipe c, which device relieves the/back pressure at. I

the outlet d. At the same time, this brings about a cooling of the material being discharged. The apparatus can also by the same mode of operation be used conversely as a cooling apparatus. F

Having thus described my invention, what I claim and desire to secure by Letters Patent of the United States is A process for treating granular material consisting in continuously passing material en masse through'an inclosed column, maintaining a mass of substantially uniform depth and body during the passage of the material through the column, introducing a drying medium into the mass of material at .the beginning of the travel of the mass and causing said medium to travel continuously through the mass in the direction of travel of the latter.

In testimony whereof I have afiixed my signature in presence of'two witnesses.

ERNST BORNMANNQ Witnesses Gnono Sormoonn, ALFRED HQFFMANN, 

